1. Field
The present invention relates generally to telecommunications, and, more specifically, to methods, apparatus, and articles of manufacture for broadcasting and multicasting from a cellular radio network.
2. Background
A modern communication system is expected to provide reliable data transmission for a variety of applications, including voice and data applications. In a point-to-multipoint communications context, known communication systems are based on frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and perhaps other multiple access communication schemes.
A CDMA system may be designed to support one or more CDMA standards, such as (1) the “TIA/EIA-95 Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (this standard with its enhanced revisions A and B may be referred to as the “IS-95 standard”), (2) the “TIA/EIA-98-C Recommended Minimum Standard for Dual-Mode Wideband Spread Spectrum Cellular Mobile Station,” also known as the “IS-98 standard,” (3) the standard sponsored by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including documents known as 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the “W-CDMA standard”), (4) the standard sponsored by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in a set of documents including “C.S0002-A Physical Layer Standard for cdma2000 Spread Spectrum Systems,” the “C.S0005-A Upper Layer (Layer 3) Signaling Standard for cdma2000 Spread Spectrum Systems,” (the “cdma2000 standard” collectively), (5) the 1xEV-DO standard “TIA/EIA/IS-856 cdma2000 High Rate Packet Data Air Interface Specification,” and (6) certain other standards. The standards listed above are incorporated by reference as if fully set forth herein, including annexes, appendices, and other attachments.
Manufacturers continue to add performance-enhancing features to wireless user equipment (UE) devices for use with cellular radio networks, such as cellular telephones. For example, many UEs include display screens with sufficient resolution to render video presentations.
With the enhanced capabilities of their UEs, users become more interested in being able to receive television broadcasts. Where there is demand, supply is likely to follow. Notably, cellular infrastructure for transmitting to UEs is already available. Operators of cellular networks thus would benefit from providing broadcast or multicast services to their subscribers. Live television, movies, sport clips, talk shows—all can be broadcast or multicast from a cellular radio network, in addition to more conventional services provided by such networks. This can be, in effect, similar to providing cable or satellite channels directly to the UEs.
Multimedia Broadcast Multicast Service (MBMS) is a broadcasting service that can be offered via existing Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) cellular networks. MBMS and its enhanced version, E-MBMS, are being standardized in various groups of 3GPP (Third Generation Partnership Project).
Downlink (DL) capacity is an important performance characteristic of cellular systems. Increased downlink capacity can be used, for example, to make more broadcast/multicast channels available to the subscribers, and to improve the quality of the broadcast transmissions. For a fixed frequency range available for cellular system transmissions, capacity depends on spectral efficiency. Given limited availability of electromagnetic spectrum, it is therefore desirable to increase spectral efficiency of cellular systems, including spectral efficiency of broadcasts and multicasts. To avoid costs associated with infrastructure updating, it is desirable to increase spectral efficiency of existing infrastructure without or with limited changes.
Many base transceiver stations (BTSs) of existing cellular radio network sites (Nodes-B) have a single transmit antenna for single frequency network (SFN) operation. There is therefore a need in the art for methods and apparatus that increase SFN broadcast and multicast spectral efficiency of cellular networks without requiring installation of multiple antennae at existing cellular sites.